Telephone system



Mar. '27, 1923. 1,449,6 1 .4

1 C. WHITE TELEPHONE SYSTEM Filed Dec. 50, 1919 5 sheets-sheet 1 125v. 7 MARGINAL //1 vekz/a r: Char/es W/? [/6 Mar. 27, 1923. 1,449,644

C. WHITE I TELEPHONE SYSTEM Filed Dec. 50, 1919.

5 sheets-sheet 2 Mar. 27, 1923.

1,449,644 CL VVHIT TELEPHONE SYSTEM Filed Dec. 50, 1919.

Z F/ fl.

S'SheEtS ShBGt 3 7 MAHGINAL //7 v6 /4 fo r: Char/e a W/7 ffe y m my.

Patented Mar. 27, 1923.

' u it STPYSJV cHAELEs' WHITE, OF EAST ORANGE, NEW

JEnsnY; Ass1Gi\Toa "r0 w sTEEn ELEcTaip COMPANY, INCORPORATED, OF NEW YORK, n.1, A CORPORATION OF NEWYORK. j

TELEPHONE SYSTEM.

Application filed December 30, 1919. Serial No. 348,324.

To all whomz't may concern- Be it known that 1, CHARLES lVHi'rE, a

citizen of the United States, residing at East.

ence to signaling means employed with,

transmission lines. I

In systems of this character, it has been proposed to employ physical and phantom lines ior interconnection between distant operators or subscribers. It has further been proposed to employ these lines for the transmission of signals ofvarious natures to signal the operators at distant ofiices and tocontrol the operation of repeater apparatus at intermediate ofiices or stations.

An object of the present invention is to provide an improved signaling circuit for use-with physical and phantom lines wherein the siniplexed physical lines are utilized,

in series with the signaling circuit,.for. the

transmission of signaling impulses designed to controlmeans which selectively determine the particular line over which a connection is tobe established.

For a complete understanding of this invention, reference 18 made to the following description taken in connection with the accompanying drawings in which Figs. 1 to 3 inclusive, with Fig. 2 arranged between Figs. 1 and 3, represent a preferredembodiment of the invention; and Fig. 4 is a diagrammatic view of one of several cord circuits employed atthe operators positions.

The invention is particularly designed for use with comparatively short toll lines and is shown as comprising two distant offices X and Z and an intermediate oflice or station Y. Two'physical lines A and C and a phantom line B are employed to interconnect the operators positions at the distant offices. At oifice X there are provided two relay mechanisms, one including relays 4, 5 and 6 and the other relay 12. These mechanisms are both. common to the lines A, B and C and areemployed for controlling the trans mission of selective filldCllSCOnIlBCt signaling impulses. The first named mechanism remains operated as long as any one of the lines is being used, while the relay 12 is energi zed only throughout the duration of a' signaling impulse. Similar mechanisms are" provided at ofliceZfor the transmission of impulses to the office X. Asignaling circuit passing throughalternate contacts of relay 12 is simplexed with the two physicallines and at oiiice ,Y there is provideda means, preferably. consisting of polar relays, 197 v and 198. the former of Whichis marginal,

said relays being in series with the signaling circuit including the physical lines extending between ofiices Xand Y. The relays 197 V and 198 are variously responsive to different potentials transmitted from office X over both physical lines to operate certain relays at ofice Y which, in energizing, transmit the same potential to oifice Z. The operation of any one of the latter relays is designe dto connect a battery supply. to the filaments of telephone repeaters RA andBC associated with the respective physical lines A and C.

This battery supply remains efiective' as long.

as any one of the lines is being used. 1 A:

mechanism at office Z, preferably including polarrelays 207 and 208, the tormerbeing marginal, is responsive to the potential transmitted from ofiice Y to control the selection of a particular one of the linesatoffice Z, whereupon a signal individual to said line is operated to inform the operator that a call is being extended over-that line. A.

, disconnect signal is transmitted ina similar manner from either terminating end. of'a line and if the other lines areidle when this. signal is sent, thesame will='operate to re-.

store the repeater apparatus to normah It is to be noted'that all slow, operating and releasing relays. employed areconventionally illustrated as such by arrows intersecting the armatures of said relays and pointing in the direction said, armatures are slow to move. 7

With this general description in mind, ity is belietied that'the invention will now be fully understood from the following detailed description of the operation;

Operator at ofiice X initiates a call one?" Zine circuit A.

The. operator at office Xdesiring to coinnuiii'cate with the operator atv oflice Z, after ascertaining thatline circuit A is free, ii-1-, serts calling plug-l3 of the selected one of the plurality of link circuits D into jack 20. The arrangement for testing the condition of the line has been omitted from the drawings since it is unessential to a proper understanding of the invent-ion, any well known system of this nature being suitable for use in this connection. Relays 14 and 21 operate over a circuit extending from battery through the winding of relay 14., the sleeve contacts of plug 13 and jack 20, and the winding of relay 21 to ground. Relay 22 thereupon operates over an obvious circuit and the closure of the right-hand alternate contact of relay 22 causes the operation of relay 4 over an obvious circuit whereupon relays 5 and 6 operate in succession. The closure of the middle alternate contact of relay 22 causes the operation of relays 12 and 27, relay 12 operating over a circuit extending from battery through the upper Winding of relay 12, the middle normal contact of relay 26, the normal contact of relay 25, and the middle alternate contact of relay 22 to ground. He lay 27 operates over a circuit extending from battery through the winding of relay 27, the left-hand normal contact of relay 68, and the right-hand normal cont-act of relay 4:8 to the middle normal contact of relay 26 where it joins the circuit traced for relay 12. A circuit is thereupon completed from the positive terminal of the 120 volt source of current through the right-hand alternate contact of relay 27, the lower alternate contact of relay 12, the simplexed conductors of line A extending from oilice X to oflice Y, the upper normal contact of relay 199, the windings of polar relays 198 and 197 in series, the lower normal contact of relay 199, the simplexed conductors of line C extending from office Y to otfice X, the upper alternate contact of relay 12, and the middle alternate contact of relay 27 to ground. The direction of current flow and the strength of such current in this circuit is such, that relays 197 and 198 close their upper contacts whereupon relays 193 and 196 operate over a circuit established from battery through the winding of relay 193, the upper contact of relay 197, and the winding of relay 196 to ground. The opening of the normal contact of relay 193 prevents the operation of slow to operate relay 195. The closure of the right-hand alternate contact of relay 193 causes the energization of relay 189 whereupon relay 191 operates over a circuit traceable from battery through the winding and normal contact of relay 191, and the contact of relay 189 to ground. Belay 191 then locks over a circuit extending from battery through the winding and right-hand alternate contact thereof, and the normal contact of relay 190 to ground. The closure of the left-hand and middle alternate contacts of relay 191 complete the current supply circuits t'or the telephone repeater equipments represented diagrammatically by the dotted rectangles RA and RC respectively, which may be of any ordinary type, the arrangement shown in Patent No. 1,413,708, issued April 25, 1922, to John Davidson, jr., being particularly adapted for use in this connection. The operation of relay 196 causes the opera-tion of relay 181 over an obvious circuit. The closure of the left-hand and middle alternate con tacts of relay 193 completes a circuit extending from the positive terminal of the 120 volt source of current through the lefthand alternate contact of relay 193, the upper alternate contact of relay 181, the simplexed conductors of line A extending from ofiice Y to office Z, the lower normal contact of relay 212, the windings of polar relays 208 and 207 in series, the upper normal contact of relay 212, the simplexed conductors of line C interconnecting offices Z and Y, the lower alternate contact of relay 181, and the middle alternate contact of relay 193 to ground. The direction of current flow and the strength of current in this circuit is such that relay 207 closes its contact, and relay 208 simultaneously closes its left-hand contact. The closure of the contact of relay 207 causes the operation of relay 229 over a circuit extending from battery through the winding of relay 229, and the contact of relay 207 to ground. Lamp 223 is thereupon lighted over a circuit extending from battery through the upper right-hand alternate contact of relay 229, the right-hand normal contact of relay 222 and lamp 223 to ground. Relay 229 locks over a circuit extending from battery through the winding and left-hand alternate contact of relay 229, and the left-hand normal contact of relay 222 to ground. Although polar relay 208 also operates to close its left-hand contact, the opening of the left-hand normal contact of relay 229 occurs before relay 269 of line C can close its front contacts and thus prevents the operation of relay 269 which is slightly slow to operate.

Slow to operate relay 27 in operating also causes the operation of slow to release relay 28 over a circuit extending from battery through the winding of relay 28, the lefthand alternate contact of relay 27, the righthand normal contact of relay ma l contact of relay 25, and the middle alternate contact of relay 22 to ground. The operation of relay 28 provides a ten'iporary ground connection at its right-hand alternate contact which is extended through the right hand normal contacts of relays 418 and 68 to maintain relay 27 energized sufiiciently long to permit the impulse of current to be transmitted. Relay 26 operates over a circuit ex tending from battery through the left-hand contact of relay 28, the left-hand normal contact and winding of relay 26, the normal 26, the norcontact of relay 22 to ground. Relay'26 thereupon locks over a circuit completed from battery through the alternate contact and winding ot' relay 26, the normal contact of relay 25, and the middle alternate contact of relay 22 to ground. The operation of relay 26 opens the original energizing circuit for relay 27 and the operating circuit for relay 28 and upon therelease of the latter relay, the connection toground at its right hand alternate contact is removed and relays 27 and 12 release. relay 2? disconnects the 120 volt source or" current from the circuit including the relays 198 and 197 atotfice Y. Relays 181, 197, 198, 193, 196, 207 and 208 thereupon release. However, relay 191 remains operated to maintain the source of current supply associated with the repeater equipments. RA. and RC. Relays 4, 5, 6, 14, 21, 22, and 26 at office X as well as relay 229 at'oflice Z remain in an operated condition. Thus the a signaling circuit is restored to normal so Winding of relay 221 to ground.

that it may be employed for the transmission thereover of signaling currents for lines B and C. I

Operator at ofice'z responds to call 01167- Zine Gimme A.

The operator at office Z observing the lighted" condition of lamp 223 associated. with the line A, inserts plug 13 of a suitable link circuit D thereat into jack 220 there upon causing the operatic-not relays 14 and 221 over a circuit established from battery through the winding of relay 14, the sleeve contacts of plug 13 and jack 220, and the .The op-- eration of relay 222 over an obvious circuit follows, thereby extinguishing the lamp 223 by the opening of-the right-hand normal contact of said relay 222. The middle alternate contact of relay 222, closing before the left-hand normal contact thereof opens,"

causes the operation of relay 226 over a circuit extending from battery through the lower right-hand alternate contact of re-' lay 229, the right-hand normal contact and winding of relay 226, the

relay 225 and the middle alternate contact of. relay 222 toground. Prior to the 'op-' oration of relay 226 a circuit is established for relay 22? extending from battery through the winding of relay 227, the righthandnormal contact of relay 268, left-hand normal contactof relay 248, middle normal contact ofrelay 226, normal contact of relay 225 a nd the middle alternate contact of relay 222, to ground. ,Ina'smuchas relay'227 is slow to operate, this relay will'not attract its armatures before the energizing circuit therefor is opened atthe middle normal contact of relay'226. Therefore, the transmission of a signal from ofiice Z to ofiice X 7 The release of this time.

normal contact of is, at this time, prevented. 'Upon'the openis opened and this relay releases. .Relay 226 v locks over a'circuit extendingfro m battery through the alternate contact and winding of relay 226, the normal contact of relay 225 222 .to ground.

Thus relay 14 Ol the se- 'lectedli'nk circuit D and relays '221, 222 and 226 o'f the line circuit A remain operated.

Theclo'sure of the left-hand alternate contact-0t relay 222 establishes aflcircuit for relay 204 which upon energizing, causes the,.,j,.

successive operation or slow'release relays 205' .and 206. However, the energization'ot these relays performs no useful function at Immediately following the insertion of the plug v13 ofthe selected link circuit D" at actuates her listening key 15, therebyassociating the, usual operators telephone set cuit Dat said 'oflice tosimilarlyassociate and the middle alternate contact of relay office X into jack'20,;the operator thereat the answeringoperators telephone set with o the latter link circuit, whereupon the two operators may communicate witheach other. In the usual. practice the initiating operator at 'ofiice X may connect the selected link cir- V cuit D thereat, in any well-known manner,

- with a calling line terminating at suchoffice and the operator at-otfice Z, in. response to in-.

structions received from the operator at otfice. X, may similarly connect the selectedlink circuit D thereat with a "desired called 9 line terminatingat oflice Z, so that the subscribers on the calling and called lines may converse.

0 9mm at 'ofiice initiates caicalloo'er Zine I I v .3110 "Desiring to contemporaneously extend an-' t 7 other connection to the office Z, the, operator circuit B.

at office X inserts another'of the plurality ot'link circuitsD thereat into the jack 40 of line B thereby operating relay '14 of theselected link circuit,:and relay of the line circuit B over a circuit eXtendingfrom'b-at.

terysleevecontacts of plug 13 and jack 40, and

the winding of relay 41, to ground. Relay 42 thereupon operates over an obvious cirthrough th winding of relay 14, the 1 cuit, the opening of the left-hand normal I contact 'thereot preventing the lighting of lamp 43. The closure ot-the middlexalternate contactot relay 42' causes the operation of relays 47' and12 the former operating circuit extending 't-rom battery.

over a throughthe winding of relay 47, the l'ettthis relay! is not energlz'ed due'to a signal ,hand normal contact of relay 28flprov'ided being transmitted for line the righthand normal contact. of relay 68, the middle normal ontact of relay 46, the l'lOl'Lull contact oi. relay 45, and the middle alternate contact of relay 42 to ground. Relay 12 operates over a circuit extenc'ng from battery through the middle winding of relay 12 to the middle normal contact of relay 4.6 where it joins the circuit traced for relay 4T. 3;. ci iit is thereupon completed from the negative terminal of the 60 volt source oi current through the right-hand alternate contact of relay 4?, the upper alternate contact of relay '12, the simplexed coudmtors ot line circuit C extending from otllce X to Otlice Y, the lower normal contact oi relay 199, the windings of polar relays 19" and 198 in series, the upper normal contact of relay 199, the simplexed conductors oi the line circuit A extending from otlice Y to oliice X, the lower alternate con tact of relay 12. and the middle alternate contact ot relay 4'? to ground. The current flows through this circuit in such a direction that relay 19S closes its lower contact. However, the amount of current flowing therethrough is insutlicient to cause the operation of the marginal relay 197. Relays 194 and 196 thereupon operate over a circuit extending from battery through the normal contacts of relays 192 and'19-3 in series, the winding of relay 194, the lower contact of relay 198, and the winding of relay 196 to ground. As previously desc *ibed, relay 196 causes the operation of relay 181 over an obvious circuit. Relay 189 also operates over an obvious circuit including the right-hand contact of relay 194. However, as previously described in detail, relay 191 is locked independently of relay 189 and consequently no effect is produced thereby. A circuit is also completeo extending from the negative terminal of the 60 volt source of current through the leftshand contact of relay 194, the upper alternate contact of relay 181, the simplexed conductors of line circuit 14. extending from otlice Y to otlice Z, the lower normal contact of relay 212, the windings of relay 207 and 208 in series, the upper normal contact 01 relay 212, the simplexed conductors of line circuit C extending from cities Z to office Y, the lower alterate contact of relay 181 and the middle contact of relay 194 to ground. The direction of current flow and the amount of current flowing in this circuit is such that re lay 208 closes its right-hand contact, while marginal relay 20? remains unaffected thereby. Relay 249 operates oyer a circuit extending from battery through the winding ofrelay 249, the right-hand contact of relay 208, and the normal contact of relay 229 to ground. Relay 249 is thereupon locked over a circuit established from battery through the winding and left-hand alternate contact of relay 249 and the left-hand normal con tact of relay 242 to ground. Lamp 243 is lighted over a circuit extending from battery through the upper right alternate contact of relay 249, right-hand normal contact of relay 242, and lamp 243 to ground.

Relay 4? in operating as previously desribed also causes the operation of slow to release relay 48, over circuit extending from battery through the winding of relay the lett-hand contact of relay 47, the right-handnorn al contact of relay 46, the normal contact of relay 45, and the middle alternate contact of relay 42 to ground. Relay 46 then operates overa circuit extendin from battery through the left=hand alternate contact of relay 48, the right-hand normal contact and winding of relay 46, the normal contact of relay 45, and the middle alternate contact of relay 42 to ground. Relay 46 looks over an obvious circuit. The operation of relay 46 opens the circuit for relay 48 which, after an interval, releases to open the circuits for relays-47 and 12. Relay 4? is thus released, disconnecting the 60 volt source of current and ground from the circuit including relays 197 and 198. There upon, relays 198, 194, 196, 181 and 208 release. However, relay 191 remains operated to maintain the source of current supply associated with the repeater equipments RA andliC and in addition to the relays mentioned in connection with the call over line A, relays 42, 46 and 249 remain in an operated condition. The signaling circuit is thereupon restored to normal. closure of the right-hand alternate contact of relay 42 completes a circuit including the winding of relay 4, no effect is produced upon the system inasmuch as relays 4, 5 and 6 are maintained in an operated condition due to the closure of the right-hand alternate contact of relay 22.

Operator at 077506 Z answers the call emtended coer- Zz'ne circuit B. I

The operator at 'otfice Z, observing the lighted condition of lamp 243, inserts the plug 13 of another link circuit D t-hereat into jack 240 thereby causing the operation of relay 14 of the selected link circuit,:and relay 241 of the line circuit B, over a circuit extending from battery through the winding of relay 14, the sleeve contacts of plug 13 and jack .240 and the winding of relay 241 to ground. Relay 242 thereupon operates over an obvious circuit, the opening of the right-hand normal contact thereof e1:- tinguishing the lamp The middle alternate contact of relay 242 closing before the left-hand normal contact thereof opens causes the operation of relay 246 over a circuit extending from battery through the lower right-hand alternate contact of relay 249, the right hand normal contact and Although the of relay 222.

. Operator at "from battery through the winding of 'relay g for is disabled by the opening of the middle normal contact of relay 2&6 so that the transmission of a signal from office Z to office Y is prevented. Relay 249 is released upon the opening of the left-hand normal contact of relay 2 12. In operating, relay 246 looks over a circuit established from battery through the alternatecontact and Winding of relay 246, the normal contact of relay 2 15 and the middle alternate contact 01- relay 242 to ground. Thus relay 1% ofthe selected line circuit D' and relays 2&1, 2&2 and 246 of the phantom line circuit B remain operated. The closure of the left-hand alternate contact of relay 242 produces no material effect upon the system since relay 20a is maintained in an operated condition by means As'in the case of the initiationot the call over line circuit A the actuation of the as sociated listening keys 15 enables the operators to converse over the phantom line circuit B and to proceed to establish a con nection betiveen'calling and called lines.

office X initiates a callover Zine circuit 0.

Desiring to contemporaneously extend another connection from the oiiic'e X to the Uil'lCG Z, the operator at oiiice X inserts the plug 13 of another link circuit D thereat, into the: jack 60 thereby operating relay 1 1 ol' the selected link circuit," and relay 61 oi. the line circuit C, over a circuit extending i l, the sleeve contacts of plug 13 and jack 60, and the Winding of relay 61 to ground. Relay 62 thereupon operates over an obvious circuit. The closure of the middle alternate contact of relay62 causes the operation of relays 67 and 12, the former operatingove'r a circuit extending from battery through the Winding of relay 6?, the lefthand normal Contact of relay 48, the righthand normal contact'oi' relay 28, the middle normal contact of relay 66, t 1e normal contact of relay 65, and the middle alternate contact of rela-y62 to ground, and the latter operating over a circuit-extending from bat-- tery through the lower winding of relay'12 to the middle normal Contact of relay 66 Where it joins the circuit traced for relay 67.

e44 A circuit is thereupon completed from the positive terminal of the 60 yoltv source 0t current through the right-hand contact of relay 67 ,the upper alternate contact ofrelay 12, the simplexed conductors of line cirs cuit C, extending from oiiice X to ofice Y, the lower normal contact of relay 199, the windings of relays 197 and 198 in series, the upper normal contact of relay 199, the sim- )lexed conductors of line circuit A eXtend-;. X, the'lower aling from otiice Y to cities ternate contact of relay 12, and the mddle alternate contact of relay 67, to ground.

The direction of current" fiowthrough this 7 circuit is such that relay 198 closes its upe;

per contact but the amount of current insufficient to cause relay 197 to closefits upper contacts. Therefore, relays 195; and 196 operate over a circuit established from battery through the normal contacts oi rem lays 192 and 193 in series,the.winding'oi":

relay 195, the upper contact oih'elay 198, and the Winding of relay 196 mgr-Quad. As before, the operation of relay 196 causes the operation of relay181. The closure of the right-hand contact of relay 195. operates relay 189 over an obvious circuit but no material .eflect is produced thereby since: relay 191 remains locked in an operated condition due. to the call initiated over line circuit A. A circuit is also completed from the posi-y tiveterminal of the 60 volt source of current through the left-hand contact ofrelay 195, the upper alternate contact of relay 1 61, the simplexed conductors of line circuit 31 extending from mice Y 'torofiice Z, the lower normal cont-act of relay 212, the windings of relays 208 and 207Iin series, the upper normal contact of relay'212, the simple-Keri, conductors oi line circuit 0 extending ironioiiice Z to'oiiice Y, the louver alternate contactot'relay 181, and the middle contact of V relay 195 to ground. The direction otcurrent flow in this circuit is such that relay 208 closes its left-hand "contact, while theh amount of current flowing therethrough is such that marginal relay 207 does not respond, therefore relay 269 operates over a.

circuit extending from battery through the winding of relay 269, the left-hand cont-act of relay 208 and the normal contact of relay 229 to ground. Lamp 263 is thereupon lighted over a circuit extending irom battery through the upper right alternate c-on- I tactof relay 269, the right-hand normal contact of relay 262 and the'lamp 263 to ground.

The operation of relay 67 as previously, described also causes the operation ofsloW to release relay 68 over a circuit extending from battery throughthe winding of relay 68, the left-hand contact of relay 67, the

:right'hand normal contact of, relay 66, the

normal contact of relay 65, and the middle alternate contact of relay 62 to ground.

"When relay 68 has operated relay 66 operates over a circuit extending from battery through the left-hand alternate contact of relay 68, the left-hand normal contact and Winding of relay 66, the normal contact of relay 65, and the middle alternate contact of relay 62 to ground. Relay 66 in operating looks over a circuit established from battery through the l ft-hand alternate contact and Winding of relay 66, the normal contact of relay 65 and the middle alternate contact of relay 62 to ground. The opera tion of relay causes the release of? relay which, after an interval, restores its armatures thereby opening atits right-hand iternate contact the circuit for relay 6?. The release oi relay also releases relay 12. Relay 67 thereupon releases to disconnect the 60 volt source of current connected from the circuit previously traced as including relays 197 and 198 at otice Y, and relays 181, 198, 195 and 208 also release. However, relay 191 remains operated to maintain closed the battery supply circuits for repeaters RA and RC and in addition to the relays mentioned in connection with the previous calls relays 62 66 and 269 remain o1 erated. its in. the pr vious cases the signaling circuit is" restored to normal and rendered available for further use.

Although the closure of the right-hand alternate contact of relay 62 completes a circuit including the winding of relay 4 no effect is produced thereby since relays 4, 5

and 6 are maintained in an operated condition due to the closure of the correspond ing contacts of relays 22 and L2.

Operator at ofiice Z answers call extended over a Zine circuit C.

The operator at otlice Z observing the lighted condition of lamp 263 inserts a plug; 13 of another selected link circuit l) thereat into jack 260, thereby causing the operation of relay 1st ofsuch link circuit, and relay 261. of line circuit C. over a circuit extending from battery, through the winding of relay 1%, the sleeve contacts of. plus 13 and jack 260, and the Winding of relay 261 to ground. Relay 262 thereupon operates over an obvious circuit extinguishing lamp 263 and upon opening its left-hand normal contact releases relay 269. However, the middle alternate contact ot relay 262, closing before the left-hand normal contact thereof opens, causes the operation of relay 266 over a circuit established from battery through the lower right-hand alternate contact of relay 269, the right-hand normal contact and Winding of relay 266, the normal contact of relay 265 and the midddle alternate contact of relay 262 to ground. Prior to the operation of relay 266 a circuit is completed from battery through the Winding of relay 267, the right-hand normal contact of relay 248, the left-hand normal contact of relay 228, the middle normal contact of relay 266, the normal contactot relay 265 and the middle normal contact of relay 262 to ground. However, due to the slow operating nature of relay 267 such relay does not complete its operation before the energizing circuit just traced therefor is disabled by the opening of the middle normal contact of relay 266 so that thetrans mission 01" a signal from otlice Z to otlice Y is prevented. Relay 269 is now released upon the opening of the left-hand normal contact of relay In operating, relay 266 locks over a circuit completed from battery through the alternate contact and Windof relay 266, the normal contact of relay 265 and the middle alternate contact of relay 262 to ground. Thus relay 1% of the selected link circuit D at ofiice Z and relays 261, 262 and 266 of line circuit C remain operated. The closure of the left-hand alternate contact of relay 262 produces no material ellect upon the system since relays 204:, 205 and 206 are maintained operated due to the closure of the similar contacts of relays 222 and 242.

As in the previous cases the actuation of the associated listening keys 15 enables the operators to converse over the line circuit C and to proceed to establish -a connection between calling and called lines.

Operator of 077206 X transmits disconnect signals to the operator at ofiioe Z.

Upon the completion of the conversation over line circuit A, the operator at oilice X actuates ringing key 18 in the link circuit D connected with the line circuit A, thereby operating ringing response relay 25 over a circuit extending from the source of alternating current, through the lower alternate contact of key 18, the ring contacts of plug 13 and jack 26, the lower normal contact of relay 24, one Winding of the repeating coil, condenser 35% and the Winding of relay 25, shunted around condenser 32, the upper normal contact of relay 24, the tip contacts of jack 20 and plug 13, and the upper alternate contact of key 18 to ground. The condenser 32 in the tip conductor of the line circuit is so proportioned relative to the condenser 84: that the shunt circuit including the latter condenser and the Winding of relay 25 is resonant for the usual frequency of ringing current. Slow release relay 30 thereupon operates over an obvious circuit to short-circuit the Winding of the repeating coil thereby preventing the ringing current being induced into the other section of the line circuit A through such repeating coil. The opening of the normal contact of relay 25 causes the release of relay 26. Upon the cessation of the application of the alternating current, relay 25 releases, thereupon dition. The supervisory relay 16 of the link reestablishing the conditions e aistingsubsequent to the insertionof plug 13in jack 20 upon the initiation of. the call sotha t the operations described in connection with the transmission of the calling signal for 'line circuit A to, and including the'opera-tion of relay 229, tollowas-previously described. However, the operation of relay 229 causes the operation of relay 224 over a circuit-"extending from battery through the upperright-hand.alternate contact of relay :229,

the right-hand alternate contact of relay 222 and thewinding of relay-i224 to ground. Relay 229 does .not look as in the'previous case since. relay 222. is in an operated-concircuit D, associated-With the line A at oflice Z operates over a circuittextending from the source otalternating current through the lower alternate contact of 'relayf224', the

ring contacts of jack:220 and plug 13, the

.lowernormal contact of key 18, left-hand winding-of relay 16, condenser 19, the upper normal-contact of key 18, the tip contacts of plug,

-. upo'n lighted over acircuit extendingfrom lit ' 'ive a a i oflice' Z in the manner described iii-connecnormal.

circuit D at office Z ffromzjack 220 -battery,.through thecontact of relay 1l,the

contactl offkey'15, the} lower contact and, right 'Winding-of' relay 16 to ground.

The subsequent removal of plug 13oflink and of plug 13 of link circuit D at office X-from jack 20 restores all apparatus at oilices-X and Z of line. circuitA to normal.

Upon the completion of-the conversation 1 overthe phanton, line circuit B, the operator at-otliceX actuatesringingkey 18 of the link circuit D connected with the line circuit-B :at office X,thereby operating relay I over a circuit similar-to that traced or relay25 'and causing the subsequent operation ofrelay in a manner similar to-that described for relay 3O' and also releasing relay 46. Upon the release of theringing key an impulse is transmittedto the oliice Z .to cause the operation :of relay 24:9 in a manner similar to that described in connectionwvith the initiation of the call over the line circuit'B. However, as described in connection With the transmitting of the disconnect signal-over the line circuit A, relay 244 is 1 operated over a circuit extending from battery, through the upper right-handalterna-tc contact of relay 249, the right hand alter 'nate contact of'relay 24:2, and the winding of relay-24 to ground. Relay 16 in the link circuit D associated with the line cir-' =cuit B at ofiice Z is thereupon operated to light the associated supervisory lamp '17 to disconnect signal to the operator at tion With the line circuit A. The subse- 13 and jack 220, and the upper altera hate contact of -relay.224c.to ground. Supervisory lamp .17 :inrthe link circuit associated with? the line circuit A. at office Z'isthereparatus individualwto the'line circuit G5 at laysa r for line- A is a Also, relays 186, 187, and 188 are-icontrolled' release relays -5 battery, lay 12, the left-hand alternate-contact ofre crates to complete que nt removal of the link circuit: D from association with line circuit B restores to normalall'apparatusfor such line circuits at I offices Xand Z. v I

In a similar manner, the actuationof therin'ging 'key l8f'in' the: link circuit D associated'w1ththe line circuit C at oflice X upon the completion of the conversation over such line causes the operation of relays and and the release of relay66. The release of theringingkey transmits an im-' pulse tothe-oilice Z foroperating relay 269 as in the case of the initiation of the'call over such line circuit. As described in connection With the disconnect signal-tor the? other 'line'circuits, however, relay 264 is; operated over a circuit-extending from'bat tery through the upper right-hand alterr nate contact of relay, alternate contact of relay 262 and the W-ind--"- ing of relay 26 i to ground *As before, the surpervisory relay in the associated. link circuit at otl'icev Z is operated rename the 3 lighting of the associated supervisory lamp to give-a disconnect signal'to the operator at oflice Z. Inthis case, the r'emovalof the 269, the right-hand I i plugs '13 of the associated link circuits'D 1 from thejacks'60 and 260 of line circuit =0 causes the 'restoratiomto-norrnal of all -apthe oflices X and Z.

1 In. sending the disconnected signal from oilice Z, relays-225 and 230' of line A, re-

lays 2 l5 aria-250; of line Bfiand relaysr265.

and 270 of line ,C are controlled in the same manner -as'xdescribed in connection Fwith 're- 25 and 30wvhen the disconnectsignal transmitted from office X.

in amanner similar to thatiof relays 196," 197 V and 1'98 when I signals" arextransniitted from office Z.

lay 6, 'anc'l-the'left hand normal contact of relay 4 to'ground. Relay '12 thereupon'opvfor this :period' ai -circuit extendingfrom'the negative terminal ofthe' 120 volt source o-fcurrent through the rightr' hand alternate contact of relay" 6,' the right- I hand normal contact of relay l, the lower T he repeater equipment/ saac rendered inthe releaseot relay 4, slow relay 197,

and the amount of current 7 this circuit 1s such that relay 197 and 1% close their lower contacts. The closure of the lower contact by relay 197, causes the operation of relays 192 and 196 over a circuit extending from battery, through the winding of relay 192, the lower contact of and the winding of relay 196 to ground. The closure of the alternate contact of relay 192 operates relay 190 over an obvious circuit and the opening of the contact of the latter relay releases relay 191 so that the filament currentsupply circuits of repeaters RA and RC are opened. The opening of the normal contact of relay 192 removes the battery connection from one terminal of the winding of slow to operate relay 194 so that such relay does not operate. As in the previous cases, relay 196 in operating causes the operation of relay 181 but no material efl'ect is produced thereby.

Although in each case the transmission of the signals has been described as being initiated at oflice X and received at oflice Z it is evident that sincethe equipments at the two ofiices are duplicates, such signals may be transmitted from oflice Z to oiiice X with equal facility. Also due to the arrangement of the apparatus atofiice Y it is apparent that the repeaters can be controlled from either oifice X or Z and the signals repeated in either direction. Although the system has been described as including the intermediate oitice or station Y at which the repeating equipments are placed and provision is made for repeating the signals received from either of the widely separated otficies or stations X and Z it may be pos sible to omit such intermediate stations on comparatively short line units. Likewise in connection with extremely long lines itmay be necessary to introduce several intermediate repeater stations of the type shown in Fig. 2.

From the above description it will be ap parent that four conductors interconnecting two widely separatedofiices may be em ployed for three line circuits all of the se lective signaling being transmitted over the phantom circult. It wlll also be obvlous that the filament current-supply circuits of the repeater sets are closed when any one of the line circuits 1s selected for use and are maintained in an operative condition as long as any one of the lines is 1n use.

What 1s claimed 1s:

1. In a telephone system, two distant. positions thereat, physical cilices, operators and phantom lines connecting said offices, a signaling circuit including conductors connected to certain of said lines. means for transmitting a signalling impulse for any one of said lines over said signaling circuit.- means at one office common to saidphysical and phantom lines-andoperated only when a signaling impulse torany one of them is transmitted,- and means at the other office responsive to the operation of the last-named" means for selectively lndicating and phantom linesand operated only when a signaling impulse for any one of them is transmitted, and means at'the other otfice responsive to the operation of the last-named means for selectively indicating at said other oflice the line over which a call has been initiated.

3. In a telephone system, two distant offices, physical and phantom lines connecting said oiiices a signaling circuit connected to said physical lines, means responsive to the initiation of a call on any one of said lines for transmitting a signaling impulse over said signaling circuit and said physical lines in series. means at one oflice common to said lines and operable when a call is initiated for rendering said signaling circuit effective, and means at the other oflice responsive to the operation of the last-named means for selectively indicating at said other office the line over which a call has been initiated.

4. In a telephone system, two distant offices, a plurality of transmission lines connecting said ofiices, a signaling circuit connected to certain of said lines, means for transmitting a signaling impulse for any one of said lines over said signaling circuit, a relay at one office common to said lines and operated only when asignaling impulse for any one of them istransmitted, and polar relays at the other office responsive to the operation of the first-named relay for selectively indicating at said other oflice the line over which a call has been initiated.

5. In a telephone system, two distant officcs, an intermediate otfice, a plurality of transmission lines interconnecting said offices, a signaling circuit connected to certain of said lines, means for transmitting a signaling impulse for any one of said lines over said signaling circuit and the lines to which said circuit is connected, means at one of said distant oflices common to said lines and operated only when a signaling impulse for any one of them is transmitted, 'polar relays at said intermediate office in series with said signaling circuit and the lines to which said circuit is connected, said polar relays being responsive to a signaling impulse transmitted over said signaling circuit, and polar relays at the other distant ofiice responsive to the operation of the first-named polar relays for selectively determining the line at said other oflice over which a call has been ini tiated.

6. In a telephone system two distant offices, an intermediate oflice, a plurality of transmission lines interconnecting said offices, a signaling circuit connected to certain of said lines, means for transmitting a signaling impulse for any one of said lines over said signaling circuit and the lines to which said circuit is connected, means at one of said distant ofiices common to said lines and operated only when a signaling impulse for any one of them is transmitted, polar relays at said intermediate oflice in series with said signaling circuit and the lines to which said circuit is connected, said polar relays being responsive to a signaling impulse transmitted over said signaling circuit, repeater apparatus associated with certain of said lines, means responsive to the operation of saidpolar relays for rendering said repeater apparatus effective, and other polar relays at the other distant ofiice responsive to the operation of the first-named polar relays for selectively determining the line at said other oflice over which a call has been initiated.

7. In a telephone system, two distant 0ffices, operators positions thereat, a plurality of transmission lines connecting said ofiices, a signaling circuit including conductors connected to certain of said lines, means for transmitting a signaling impulse for any one of said lines over said signaling circuit, means at one ofiice common to said lines and operated only when a signaling impulse for any one of them is transmitted, means at the other office responsive to the operation of the last-named means for selectively indicating to the operator at said other ofiice the line over which a call has been initiated, other means at the first named office also common to said lines and operated when a call is initiated on any one of them, said other means remaining operated while any one of the lines is in use, and means for releasing said other means to transmit a disconnect impulse over said signaling circuit and certain of said lines in series.

In witness whereof, I hereunto subscribe my name this 26th day of December, A. D. 1919.

CHARLES WHITE. 

